Variable Drought Conditions in Minnesota

How bad is the 2012 drought[3] in Minnesota? It probably depends who you ask, and what portion of the state that you live in. Portions of central Minnesota, including much of the Twin Cities area, have received near-normal to above-normal rainfall during most of the 2012 growing season, and have very little drought stress. This has led some observers to conclude that Minnesota is not feeling much impact from the 2012 drought. However, rainfall events in much of southern and western Minnesota have been much more limited and localized, which has resulted in some moderate to severe drought conditions throughout the region.

Based on the last released U.S. Drought Monitor on July 26[4], portions of southwest and northwest Minnesota were placed in a severe drought category, while a much larger area of western and southern Minnesota was placed in a moderate drought category. Many of those areas received less than 2 in. of total rainfall from June 19 to July 26, with the driest areas receiving less than 1 in. of rainfall during that period. Topsoil moisture on 56% of Minnesota’s soil was rated as short or very short, as of July 26. Rainfall amounts over the weekend of July 27-29 provided only minimal relief from the drought conditions in many of the driest areas of the state.

Many of the rainfall events in southern Minnesota in the past six weeks have resulted in some brief heavy rainfall in relatively localized areas, with very little coverage. One location might receive an inch of rainfall, while just a few miles away the rainfall amount will be one-tenth of an inch. The University of Minnesota Research & Outreach Center at Waseca has received 2.10 in. of rainfall during July, which is below normal, but followed total precipitation amounts of 4.25 in. in June and 5.74 in. in May. It included a rainfall event of 1.03 in. on July 19, and another of 0.36 in. on July 24.

By comparison, the research center at Lamberton has received only 0.74 in. of total rainfall in July, with the largest rainfall event at 0.21 in. on July 29. The Lamberton site received only 1.26 in. of total precipitation in June, with the largest amount being 0.52 in. on June 21. Lamberton received 10.33 in. of rainfall in May, which helped replenish depleted stored soil moisture supplies. This stored soil moisture has helped maintain the crops during very dry periods in late June and early July. However, as of July 15, stored soil moisture levels at the Lamberton research center were down to 1.92 in., with most of the stored soil moisture below the 3-ft. depth.

The areas that have been fortunate enough to catch an extra rain or two, such as the Waseca area, will likely see very minimal impact on crop yields as a result of the drought, except on lighter, sandier type soils. While other areas of southern and western Minnesota, where rainfall has been more limited in late June and July, will likely see more widespread impacts from the drought. In these drier areas, it will not be unusual to see corn[5] and soybean[6] yield reductions of 10-30%, or more. Most likely, any impacts from August rainfall will be to help fully mature the crop that remains, rather than adding additional bushels to the crop yields.

The 2012 corn and soybean crop is maturing at a rapid pace. The unusually warm temperatures during the growing season have resulted in the accumulation of growing degree units (GDUs) being well above normal. As of July 30, the accumulated GDUs at Waseca were 1,764 – 18% ahead of normal the normal GDU accumulation for Aug. 13. The higher GDU accumulation in 2012, together with earlier than normal planting dates this year, puts the maturity level of most corn and soybeans in southern Minnesota approximately two weeks or more ahead of normal.

In Minnesota, just as across the U.S., the impacts of the 2012 drought are likely to be felt most by livestock producers. Livestock producers of all types will be impacted by sharply higher feed costs in the coming months, which will likely have a very negative impact on livestock profitability. In the hardest hit drought areas of western Minnesota, pasture conditions are very poor, and later cuttings of hay have experienced very low yields. Fortunately, most of Minnesota had very good hay yields earlier in the growing season, resulting in less hay shortages than in some other areas of the U.S. Based on a recent USDA announcement, livestock producers in most of Minnesota may be eligible to harvest hay from some CRP acres. Producers should contact their county Farm Service Agency[7] office for details.

Editor’s note: Kent Thiesse is a former University of Minnesota Extension educator and now is Vice President of MinnStar Bank, Lake Crystal, MN. You can contact him at 507-726-2137 or via e-mail at [email protected][8].com.